When you have a 230v or 110v relay which has 230volts or 110volts coil control voltage- what are they used for? If you think about controlling relay with a microcontroller wouldn't it be easier to have 12volt coil control voltage?

 

I always spec in 24vdc relay/contactor coils where possible, the 120/240vac coils are usually used where LV control is not available and was generally more common when all system control voltage circuits were mains powered, also all solenoids were the same, H.V. AC.
Now 12vdc/24vdc is more common and preferable.
BTW, Most reputable contactor manufacturers offer a range of coil voltages than can be changed out if required.
Max.